介质湿度对热风干燥粉丝品质形成的调控机制研究

Starch noodles are an important category of traditional food in China. Its culture is deep and has a long history. Drying of starch noodles is not only an important means for the preservation, but also a key processing operation for the quality formation. However, the related research is very limited. The modernization of traditional starch noodles processing depends on the clarification of the quality-forming mechanism of starch noodles prepared by the advanced drying technology. The traditional starch noodles prepared by natural drying possess better quality than those by hot air drying, suggesting that the medium humidity other than the drying temperature has greater influence on the quality formation of the starch noodles. On the basis in evidencing a positive influence of the air humidity on the quality of hot air-dried starch noodles, the influence of the medium humidity on the quality formation of starch noodles is to be investigated with an aim to elucidate the molecular mechanism and lay the theoretical foundation for the new drying technology developed for high-quality starch noodles. The project includes following aspects: 1) the influences of the drying medium humidity and its control mode on the quality of dried starch noodles; 2) the influences of the drying medium humidity on the quality formation with an emphasis on the evolution of multi-level structures of starch noodles (molecular level, the aggregation state, gel micro-structure, etc.) and their working mechanism; 3) the comprehensive regulating model of humidity and temperature-controlled drying and its application. The significance of this study is speculated as follows: 1) providing new cases to clarify the effects of food processing on the changes of components, food structure and function and its regulation mechanism; 2) giving new insights into developing drying methods for obtaining high-quality dried starch gels and other non-cellular food systems; 3) providing an important reference for the protection, innovation and heritage of the culture of Chinese traditional food.

粉丝是我国的一种传统特色食品，文化深厚，源远流长。干制不仅是粉丝安全贮藏的常用手段，而且是粉丝品质形成的关键环节，但相关研究十分有限。粉丝加工现代化有赖于先进干燥技术赋予粉丝品质形成机制的阐明。粉丝品质传统晾干优于热风烘干暗示着介质湿度比温度对粉丝品质形成的影响更大。本研究在确认热风干燥过程进行湿度控制有助于粉丝品质形成的基础上，重点以阐明介质湿度影响粉丝品质形成的分子机制并为创新开发高品质粉丝干制技术奠定理论基础为目标，开展如下研究：①介质湿度及其控制方式对热风干燥粉丝品质的影响规律；②介质湿度调控热风干燥粉丝品质的多层次结构（分子、聚集态、凝胶微观结构）演进机制；③粉丝热风干燥的湿度-温度联合调控模型构建及应用。该研究能为食品加工过程组分、结构与功能变化及调控机制研究提供新的内容；为淀粉浓凝胶等非细胞结构食品的高品质干制提供新的视角；对保护和创新传承我国经典饮食文化具有重要参考价值。

粉丝是充分利用淀粉老化性质制成的凝胶类传统特色食品，在大众日常饮食中占据着重要位置。粉丝生产的工序多、工艺要求高，其品质受原料、设备和加工等多重因素影响。生产经验表明，干制是粉丝品质形成的重要环节，尽管传统晾干法得到的粉丝口感顺滑，具有很好的耐煮性，热风烘干的粉丝却“筋力”弱，容易糊汤，但是，采取工业化干燥手段实现粉丝高效生产显得尤为重要。为了突破技术瓶颈，本项目主要以甘薯粉丝为研究对象，以“解析干制在甘薯粉丝品质形成中的作用及其机制、探究烘箱湿度及控湿方式对甘薯粉丝品质的影响、揭示干燥过程粉丝多层次结构演变及其品质形成机制、湿度-温度组合调控的粉丝热风干燥方法及应用”为研究思路，开展了基础理论及应用技术研究。研究发现，粉丝干燥不是一个简单脱水过程，而是涉及淀粉凝胶组分结构复杂变化的过程。粉丝中淀粉老化从粉丝熟化成型即开始发生，并贯穿粉丝加工的后续过程。干制过程粉丝中的淀粉在短程有序结构、片层结构、长程有序结构等多尺度结构上随着水分不断蒸发而不断变化，同时粉丝凝胶逐渐收缩。干燥过程淀粉老化具有温度和水分依赖性。介质湿度本质上通过控制粉丝中水分迁移及蒸发速度，从而影响粉丝的多层次结构演变和干制品的品质形成。研究结果表明，采取环境温度-相对湿度组合控制方式，即能实现通过对粉丝凝胶的淀粉老化控制来改善粉丝的品质。本项目为粉丝、粉条的工业化高效干燥打下了坚实的理论基础，同时为干燥加工因素尤其环境湿度调控干制食品品质的提供了新的思路。